An interface in the software industry could mean many different things, with the most common meaning being associated with a graphical user interface (GUI). Of course, "GUI" is the means by which users interact with a software or hardware application.

In terms of Iguana, the meaning of "interface" is quite different from the meaning of a graphical user interface (GUI). Chameleon's message definition file (VMD) is often referred to as an "interface" because it acts as a bridge between the HL7 world and Iguana, as shown in the following diagram:

Interface Overview

What's important to note is that the "interface" to Iguana is created inside the VMD file using tables. These tables describe the database tables that Iguana will "interface" with. In turn, data is mapped from incoming messages to these tables (or vice-versa).